In 1947, the US Army Air Force became independent from the Army and became the new US Air Force. At the same time, the L-2 was updated to a deep blue color of the blue sky. This jacket is just a color change from the L-2 and is named L-2A, also known as "Air Force blue" to enhance the air Force's image.
The L-2A was tested in 1950 and adopted in 1952, during the Korean War, and became popular with pilots operating on the Korean Peninsula.
Although the color of L-2A is very special and beautiful, it is not practical as a flight suit. In actual combat, if you are forced to land in enemy territory or need to take cover, the blue color is too conspicuous and is not conducive to escape. To solve this problem, the grey-green L-2B was introduced around 1955.